Traditional logistics tracking systems based on RFID technology may be implemented by either active RFID tags or passive RFID tags. Known active RFID tags possess their own power source and transmitter enabling the tag to broadcast its signal. Performance capabilities include longer read ranges and greater memory capacities when compared to passive RFID tags. However, in order to achieve a significant read range and larger memory, these performance capabilities generate a greater demand for power. Typically, active RFID tags are powered by a long life battery that will last for a few years, but will eventually require replacing.
Two different types of active RFID tags are well known—transponders and beacons. An active RFID transponder only communicates when in the immediate presence of a reader's interrogating signal, thus conserving battery life when the tag is out of range of the reader. Active RFID transponders are commonly used in secure access control and in toll booth payment systems.
Active RFID tags purposed as beacons periodically transmits their identifying information at user defined intervals and RFID reader antennas will read and determine the tag's location with the help of back-end software. This type of active RFID tag is frequently used in real-time location systems (RTLS) commonly found in outdoor shipping yards and throughout supply chains. Some active RFID tags have a read range capable of reaching 100 meters in ideal outdoor environments.
All these additional features translate to increased costs for the customer. The prices of active RFID tags depend on the tag's ability to withstand harsh conditions and other key functional features of the tag.
Bluetooth Low Energy (BLE) technology is one of the known wireless systems suitable for active RFID applications. iBeacon is a protocol developed by Apple based on BLE and various vendors have since made iBeacon-compatible hardware transmitters—typically called beacons—a class of BLE devices that broadcast their identifiers to nearby portable electronic devices. The iBeacon technology enables smartphones, tablets and other devices to perform actions when in close proximity to an iBeacon tag. Upon detecting the iBeacon tag, the mobile phone activates relevant mobile app based on its contextual search utilizing received iBeacon information and location information. In this example, different iBeacon tags can activate different mobile apps for providing promotional or campaign information to the mobile phone user.
iBeacon uses BLE proximity sensing to broadcast a universally unique identifier which will be picked up by a reader with compatible app or operating system. The identifier and data sent with it can be used to determine the device's physical location, track customers, or trigger a location-based action on the device such as a check-in on social media app or a push notification.
However, iBeacon utilizing BLE does have its obstacles to overcome if it is to be used for active RFID application. The current limitations of iBeacon approach for active RFID applications are:
1. The BLE standard offers 40 frequency channels. Among which only three broadcast channels (37, 38, and 39) can be used for iBeacon applications. This works out to a maximum possible timeslot availability of 400 (based on iBeacon broadcast interval of 100 ms and advertising packet duration of approximately 0.75 msec, i.e. (100/0.75)×3 broadcast channels) assuming no collision. For active RFID application with potentially a few thousands active RFID tags to be read by the tag reader, the iBeacon approach for BLE is not workable as the probability of collision increases with increased number of iBeacon tags.
2. The iBeacon approach broadcasts continuously whether the tag reader is present or not. This is a waste of battery life and will increase the rate of active RFID tag replacement cycle which will in turn increase the cost of use. Moreover, the broadcast approach prevents application of RFID on board aeroplanes under FAA rules which restricts equipment RF transmission on aeroplanes in flight.
3. iBeacon approach does not have reliable data handshake between tag and reader. The tag using iBeacon approach does not know whether the tag reader has successfully acquired its data as there is no acknowledgment sent by the reader to the tag. Hence, the tag has to periodically broadcast its data continuously.
4. iBeacon approach is not data secure as any BLE device can sniff and listen to the data broadcast by the tag.
There is therefore a need in the art to utilize BLE technology in an enhanced manner for active RFID application so as to gain from its low cost and low power consumption benefits and yet able to overcome the limitation of the traditional iBeacon approach.
In addition, it would be preferable if the tag reader is able to read unlimited number of tags within its range. It would also be preferable if the tag reader can quickly and reliably retrieve the identification payload from the tag. It would further be preferable to extend the battery life of the tag to last for many years.
The present invention seeks to meet these needs.